[SignalOne] LM380 vs TDA2030A

[jerry]

Hello All,

So I'm having an audio amp shootout to figure out what to put in the 
CX7A.

I have a stick of LM380's in from Mouser today.  I assembled one
dead-bug onto a scrap of single-sided bare PC board stock.  It worked.  
Then I started "improving" it by bypassing everything, and it took off 
like a bird.  Wheee!  I undid all the bypasses and it was good again.  
The culprit was the recommended .1uF/2.8-ohm series string hooked off 
the speaker output.  It's supposed to improve stability at the negative 
peaks when driving a high-current load - like a speaker, or the 8-ohm 
power resistor that I was using.

Without that recommended series string, it seems to be unconditionally 
stable.  HOWEVER, I do see a little fuzzyness on those negative peaks, 
so I guess it's making RF.  Also, at higher frequencies there's a 
smidgeon of crossover distortion.

So I just reached into the baggie of TDA2030A amplifiers that I had 
bought so very cheaply from Amazon - $10 for 8 amplifiers!

https://www.amazon.com/gp/product/B09P5VZ2KZ

One of them had died when I put too much voltage across it;  even though 
the TDA2030A itself is rated for 35V or so, the electrolytics on the 
little board were not.  Oops.  Another one died when I left it cooking 
on the bench, outputting a continuous 1 watt sine wave while I did other 
things.

At the price I got them, I wouldn't be at all surprised if the devices 
were bin rejects.

Anway, I opened another one of those baggies and set up the TDA2030A amp 
on the bench.  It's definitely cleaner than the LM380.  No crossover 
distortion that I can see, no RF at the peaks - just nice clean power.

So - maybe delivering a whole watt for hours is not a realistic test.  
Now I'm cooking that little tiny amp at 1/3W continuous.  If it does OK, 
I'm really tempted to put it in.

I saw a video of a Swedish ham who installed that exact amp in a CX7 - 
he just mounted it to the existing PS board standoff through I guess a 
longer screw.

                                   - Jerry, KF6VB